Vindicator and Justiciar are not leader positions and receive no leadership bonuses.

Tribunal has Provost + 3 Provincials (only one gets fancy powers with it).
Outlander has 3.
Battle has 2.
Fortress has 4.
Empire has 5.
etc.

Herald has had more than one High Herald before. I don't see that as necessary, or more leadership positions needed for it. If the goal is just RP powers anyway - I'm more friendly towards titles, artistries, etc. none of which require an additional leader position.